On Tue, 25 Feb 2020 at 15:19, Ethan Smith <[email protected]> wrote:
>
> The discussion on the name change came from Łukasz  
> https://github.com/python/cpython/pull/18239#discussion_r380996908
>
> I suggested "GenericType" to be in line with other things in types.py.

Quoting Łukasz question: "I know it's late for this bikeshedding but I
was always a bit puzzled by the name "GenericAlias". What is it
aliasing?"

The "GenericAlias" name seemed appropriate to me as these aren't real
types - they're aliases for the corresponding container type with some
extra metadata attached. So "list[str]" is *mostly* just a different
way of writing "list" at runtime - it's primarily typecheckers that
will treat it differently (while the runtime typechecking machinery
will reject it as too specific to be checked non-destructively).

"GenericAliasForAConcreteContainerType" would be excessively wordy
though, hence "GenericAlias".

By contrast, I'd expect something called "GenericType" to actually be
able to do full runtime typechecking and enforcement (e.g. having
instances throw TypeError if you tried to insert a value of the wrong
type).

Cheers,
Nick.

-- 
Nick Coghlan   |   [email protected]   |   Brisbane, Australia
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